民勤绿洲边缘区不同生境沙拐枣种群特征研究

沙拐枣(Calligonum mongolicum)是分布于中国北方干旱荒漠区的一种主要固沙植物，研究沙拐枣种群在沙漠不同生境中的群落特征、空间分布格局及幼苗更新，对绿洲边缘区的生态恢复和重建具有重要的意义。本研究以石羊河流域下游民勤沙井子荒漠绿洲过渡带为研究区域，采用野外调查与室内测定相结合的方法，对3种不同地貌类型（半固定沙丘、流动沙丘、丘间地）和6种微地型（半固定沙丘迎风坡、顶部、背风坡和流动沙丘迎风坡、顶部、背风坡）沙拐枣种群特征、更新苗的数量特征与土壤水分的对应关系及分布格局进行了调查分析。结果表明：（1）沙拐枣种群密度、覆盖度表现为：半固定沙丘＞丘间地＞流动沙丘，半固定沙丘和丘间地与流动沙丘之间存在显著差异(P＜0.05)，株高在流动沙丘最大，丘间低地最小，它们之间存在显著差异(P＜0.05)；而种群地径、新梢长无显著差异(P＜0.05)。（2）流动沙丘各部位密度、株高、覆盖度差异不显著(P＜0.05)，而半固定沙丘则表现为差异性显著(P＜0.05)，顶部大于迎风坡和背风坡。（3）不同立地条件下，沙拐枣幼苗数量为流动沙丘＞半固定沙丘＞丘间地，且与5~ 30 cm土壤水分含量大小相对应。（4）在民勤荒漠绿洲过渡带，沙拐枣种群呈聚集分布。

The Research on Calligonum mongolicum Population Characteristics of Different Habitat in Minqin Desert Oasis

Calligonum mongolicum is a main sand-fixation plant and widely distributed in northwest arid desert area. It is significant to research population characteristics, spatial distribution pattern, seedling regeneration of Calligonum mongolicum for ecological restoration and rehabilitation in Minqin desert oasis marginal. Minqin Shajingzi oasis-desert transitional zone in Shiyang River Basin would be selected research areas, and field investigations and laboratory surveys were carried out to research the correspondence between population characteristics, quantitative character of seedling regeneration and soil water and spatial distribution pattern on three geomorphic types（semi-fixed dunes, shifting dunes, inter-dune lowland） and micro-geography（windward slope, top, leeward slope of semi-fixed dunes and windward slope, top, leeward slope of shifting dunes）. The results showed that population density, coverage of Calligonum mongolicum showed semifixed dunesinterdune lowlandshifting dunes. There was significant difference between semi- fixed dunes, interdune lowland and shifting dunes. There was significant in plant height between shifting dunes and inter-dune lowland, plant height of shifting dunes was the biggest, but plant height of inter-dune lowland was the smallest. There was no significant in basal diameter and new shoots among 3 geomorphic types. There was no significant in density, plant height, coverage among all parts of shifting dunes, but there was significant of inter-dune lowland, and density, plant height, coverage of top was higher than windward slope and leeward slope. Seedlings amount was shifting dunes〉semi- fixed dunes〉inter- dune lowland,seedlings amount correspond to soil water in 5-30 cm. Spatial distribution pattern was dumped in Minqin desert oasis marginal.